1. Field of the Invention
The present invention is related to a method for correcting the optical axis of a laser projecting device in order to have the optical axis coincident with a central axis of the laser projecting device, and in particular, to a method which detects the spatial deviation between the optical axis and the central axis and applies a force to deform a deformable holding member of the laser projecting device in such a way to make the optical axis coincident with the central axis.
2. Description of the Prior Art
Laser projecting devices have been widely used. The laser projecting device usually comprises a laser generation unit, such as a laser diode, to generate a laser beam. A control circuit is used to control the operation of the laser generation unit. A focusing lens may be provided to more precisely focus the laser beam generated by the laser generation unit. Such a laser projecting device has been used in a variety of fields, such as the so-called laser pointer which incorporates the laser projecting device in a pen-configured holder so as to generate a highlighted spot in front of the xe2x80x9cpenxe2x80x9d, serving as visual indicating means. Other applications of the laser projecting device include, for example, use with a range-finder, a sighting device and a leveling instrument. FIG. 1 of the attached drawings shows an example of a laser generation unit which is designated with reference numeral 1 in the drawings. Commercially, the laser generation unit 1 is usually a metal-cased element having a transparent window 11 through which the laser beam is projected. The laser generation unit 1 has a plurality of terminal pins 12a, 12b and 12c through which the laser generation unit 1 is powered and controlled.
FIG. 2 shows the structure of a conventional laser projecting device which includes an elongated cylindrical tubular member 3, serving as a holder, inside which the laser generation unit 1 is fixed and held. The holder that holds the laser generation unit 1 therein will hereinafter be referred to as the laser holder. A circuit board 2 on which a control circuit is provided is attached to the laser holder 3 and is provided in electrical connection with the laser generation unit 1 through the terminal pins 12a, 12b and 12c. The laser holder 3 may include a focusing lens 30 positioned in front of the laser generation unit 1 to provide a more precise focusing effect for the laser beam. Besides holding the laser generation unit 1, the laser holder 3 also serves to protect and shield the laser generation unit 1.
To have the optical axis of the laser beam projected out of the laser projecting device in a manner coincident with a central axis of the laser projecting device, the design, manufacture and assembly of the laser projecting device requires close tolerance, otherwise the laser beam projected from the laser projecting device may suffer considerable spatial error or deviation of its spatial position/orientation. Such errors include an angular deviation between the theoretical axis of the laser generation unit and the central axis of the laser holder, which is usually within the range of 3 degrees, and a position deviation in either, the X-axis, Y-axis or Z-axis between the laser generation unit 2 and the laser holder 3, which is usually within the range of 80 microns. Such errors are generally unacceptable in applications that require high position precision. The angular deviation is also referred to herein as optical error, and the position deviation is also referred to as herein mechanical error.
To correct spatial errors, a previous attempt provided a plurality of bolts engaged within inner-threaded holes formed on the laser holder 3 and in contact engagement with the laser generation unit 1 located inside the laser holder 3 so that by adjusting the relative positions of the bolts with respect to the laser holder 3, the orientation of the laser generation unit 1 inside the laser holder 3, and thus the projecting angle of the laser beam generated thereby, are controllable. Such a method, although effective in eliminating the error of angular deviation, complicates the structure of the laser holder 3. Furthermore, it is very difficult to minimize the size of the laser projecting device if such a correcting method and structure is used. Moreover, such a method and structure may correct the optical error but this structure and method is generally unable to overcome the mechanical errors.
Thus, there is still a need for a method to correct the spatial deviation between the optical axis and the central axis of the laser holder so as to overcome the problems encountered in the prior art.
An object of the present invention is to provide an apparatus and method for correcting the optical axis of a laser projecting device so as to have the optical axis coincident with a central axis of the laser projecting device.
Another object of the present invention is to provide a method which is capable of correcting the optical axis of a laser projecting device in a ready and easy way without incorporating a more complicated structure.
The objects of the present invention may be achieved by providing a method of correcting an optical axis of a laser projecting device. According to this method, a cylindrical tubular member is provided, the tubular member made of a deformable material and having a base section, and a laser generation unit mounted inside the base section and adapted to project a laser beam along an optical axis. Thereafter, the tubular member is rotated while projecting a laser beam from the tubular member towards a reference point in front of the tubular member that corresponds to a rotational axis of the tubular member. A spatial deviation between the optical axis and the reference point is detected, and the base section of the tubular member is deformed based on the spatial deviation to cause the base section to be angularly displaced with respect to the tubular member until the optical axis and the rotational axis coincide.
According to one embodiment of the present invention, the tubular member is provided with an extension section and a reduced-diameter circumferential groove between the base section and the extension section, and the base section is deformed with respect to the extension section about the circumferential groove.
The above objects and other feature, advantages and objects of the present invention will become apparent from the following description of a preferred embodiment thereof with reference to the attached drawings, wherein: